Process for the production of alloys of the alkaline earth metals with lead or other metals



Patented Feb. 18, 193E PROCESS FOR THE PRODUCTION OF AL- LOYS OF THE EARTH METALS WITH LEAD OR OTHER METALS I Gustafflewton Kirsebom, Oslo, Norway, assignor to Calloy limited, London, England, an English joint-stock company No Drawing. Application December 22, 1932, s ug: No. 648,443. In Great Britain June 11,

9 Claims. (Cl. 751) This invention relatesto a new or improved method of process for the production of alkaline earth metals and alloys thereof with lead or other metals such as are hereinafter defined.

I ere are certainmetals, especially lead, and

cadmium which do not readily alloy with aluminium when both are in a molten condition and in the presence of each other, e. g., when molten lead is added to a bath of molten aluminium (or whenlead and aluminium are melted together) these two metals will not form an alloy but will form separate layers which are not substantially soluble in each other; and this I utilize in the process according to the present invention for the production of alloys of the alkalineearth metals with lead or cadmium or other metals of the kind which do not readily alloy withaluminium.

In my co-pending application for U. S. Patent Serial No. '620,574-filed 2nd July, 1932, I have described a process for producing alloys of the alkaline earth metals with aluminium (e. g. calcium-aluminium alloy, strontium-aluminium alloy, etc.) by the reduction of compounds of alkaline earth metals by aluminium and the production thereby of said alloys of aluminium; such process being carried out by introducing one or more compounds of the alkaline earthmetals in pieces not less thanabout 1 mm. size into a bath of molten aluminium thereby to reduce said compound or compounds and alloy said alkaline earth metal or metals with the aluminium.

Now the present invention is as f.o1l0wsi- I have found that alloys of the alkaline earth metals with lead and cadmium (or with other 3 metals which latter do not themselves readily alloy with aluminium under the conditions above referred to) can be produced, readily and economically by reducing a compound of an alkaline earth metal in a bath of molten aluminium (e. g. in the manner hereinbefore referred to) and, either before, during, or after, introducing said compound of the alkaline earth metals into said bath of molten aluminium, admixing or otherwise bringing-lead or cadmium fior other such metal as aforesaid) in a molten condition into contact with the molten aluminium alloy whereupon the alkaline earth metal leaves the aluminium and goes to the lead' or cadmium (or other such metal as aforesaid) and alloys with the lead (or other such metal .as aforesaid).

It is to be understood that'the alkaline earth (metals can be prepared-by they process of the present invention-not only from the alkaline earth metal oxides but also from other compounds of the alkaline earth metals, fox-example from the alkaline earth metal silicates.

. In the process as set out above it must be understood that the term.alkaline earth metals" includes not only calcium, strontium and barium,

but also magnesium and beryllium.

Where cadmium is employed in place of lead v the procedure is similar and when the alloy of cadmium with the alkaline earth metal has been formed-on completion of the process-the cadmium can be distilled off so that the process affords a ready means of preparing the alkaline earth metals in substantially pure condition.

Broadly stated therefore the present invention is for a process for preparing the alkaline earth metals and alloys thereof, which process comprises the steps of mixing together in the molten condition a metal which does not readily form an alloy with aluminium and an alloy with aluminium of the said alkaline earth metal or metals and allowing the melt to form into two, layers and separating the aluminium.

According to a further feature of my present invention the alkaline earth metals can be separated from'the metal (e. g. lead or cadmium) which does not readily alloywith aluminium as aforesaid; and this separation can be effected by the step of volatilizing off the volatile. metal from the alloy containing it whereby the alkaline earth metal remains alone; and pure alkaline earth metal can thus be obtained.-

The invention will now be more specifically described with the aid of examples.

In the case of lead:-

(a) The aluminium alone may first be placed in the heating chamber and melted; and after the alkaline earth metal oxides in pieces or lumps have been placed on the bath of molten aluminium and reduced and an alloypof alkaline earth metal or metals and aluminium has thereby been formed as aforesaid; thereupon lead in a molten condition (or otherwise) is introduced into said bath of molten aluminium alloy through which latter the lead will descend and settle below same in the-heating chamber; or-*- (b) ,The lead and aluminium may be, natea (melted) together in a suitable heating chamber .or the lead may be heated (melted) first and then the aluminium; and thereafter the alkaline earth metal oxides in other than powder form, 1. e. in pieces or lumps, introduced by placing said pieces or lumps on top of the molten aluminium.

whereupon, whichever procedure is followed,

itwillbefoundthatthealkalineearthmetal or metals in the aluminium will have left the latter and gone into the lead and in alloy therewith.

Or an alkaline earth metal alloy of aluminium may be melted down and molten lead added to the melt and thereupon the lead will extract the alkaline earth metal from the aluminium thus forming an alkaline earth metal alloy with the lead, which latter will sink to the bottom leaving the aluminium on top of the bath substantially free from alkaline earth metal.

For example, I have in this way melted down a calcium aluminium alloy containing 10% calcium, viz. I have melted same at about 700-l000 C.; and, after having melted some lead at about 350 C. I have added this molten lead to the alloy bath; and on pouring out this melt I found that after cooling, there were present two different layers the top one consisting of substantially pure aluminium and the bottom layer of lead containing 6.5% Ca and containing but small traces of aluminium.

In a similar manner I have made strontium lead from strontium-aluminium alloy by pouring molten lead over the molten strontium-aluminium alloy, and in this way obtained a strontium lead of a crystalline structure and analyzing 5.3% strontium.

In a similar way I have produced barium lead containing 3% barium.

Similarly magnesium was introduced into lead from a magnesium-aluminium alloy containing up to 5% Mg; and a magnesium lead alloy obtained running up to 2% Mg.

Also beryllium has been obtained in the lead or cadmium in this way.

In the case of beryllium; the following is an example of carrying my present invention into practice:-

To a molten bath of aluminium heated to about 1100 C. I add thereto natural beryl (in lumps or pieces) which is a mineral consisting of a beryllium aluminium silicate with a formula 3Be0. A1203. 6SiO2. I

By adding gradually the beryl in pieces to the metal (molten aluminium) this latter I found gradually rose in silicon content and I ended up with a metal containing 20% silicon, having thus reduced the silica in the beryl to silicon which alloyed with the aluminium. Al-

though I have so far been unable to analyze this alloy for beryllium (the analysis of this metal with the presence of aluminium being extremely difiicult) I have found that the alloy had' a steel grey appearance suggesting the presence of beryllium. By then treating this allow (berylliumaluminium-silicon) with cadmium in the aforesaid manner, an alloy of cadmium and beryllium was formed (the cadmium becoming quite brittlewhich suggested that the beryllium had gone into the cadmium) and thereafter the cadmium can be distilled off thus leaving metallic beryllium.

I have found that the migration of the alkaline earth metal or metals into the lead takes place with great rapidity; e. g. only a few minutes after adding the lead the melt could be P ured.

I have also found that if pure aluminum is melted down and alkaline earth metal oxide in lump form, that'is, in pieces and not in powder, added the melt being left for some hours at about 1200 0., an alloy will be formed. When the temperature of this alloy has dropped between 700 and 1000 C., the lead can be poured into this molten alloy and allowed to settle therethrough. This enables the process to be carried out in one operation.

I have carried out this operation in a graphite crucible which was heated in a furnace of usual type to the desired temperatures.

Any suitable type of furnace can be used for the operation.

I have found that a great recovery of the alkaline earth metal or metals was obtained in the lead, inthe case of extracting calcium from calcium-aluminium alloy by means of lead, viz. as much as 90% of the calcium went into the lead, while not a trace of calcium was found in the remaining aluminium.

I have further found that it is possible to get higher percentages of the alkaline earth metal into the lead by passing the total amount of the lead (or other such metal) to be passed once (or more than once if desired) through the bath of molten aluminium alloy slowly and yell distributed throughout the bath in order to obtain a better contact of the metals.

A convenient way of securing good distribution of the lead throughout the bath is to add the lead in granulated form to the molten bath.

Furthermore (as aforesaid) the production of the aluminium alloy is not confined to oxides of the alkaline earth metals as starting materials but other compounds may be used and in particular silicates. Thus if burnt magnesite rich in silica (l6 per'cent) is used, an aluminiummagnesium-silicon alloy is produced. In the same way other alkaline earth silicates produce the triple alloy of aluminium silicon and alkaline earth metal. When this triple alloy is treated with lead or cadmium the alkaline earth silicide in the alloy is broken up, the alkaline earth metal going to the lead or cadmium and the silicon remaining with the aluminium.

Where cadmium is employed in place of lead the temperature of the aluminium alloy bath is lowered, for example, to 700-800 C. and then the cadmium in a molten condition is poured gradually into this bath.

The process of the invention may e carried out with more than one alkaline earth metal in the alloy with aluminium.

The amount or proportion of lead or cadmium etc. to be added to the molten bath of aluminium alloy will depend on the results it is desired to obtain.

For example with equal proportions by weight of the aluminium and lead the percentage of the calcium in the aluminium (before transfer) will be about the same in the lead (after transfer); while with a smaller percentage of lead there will be a higher percentage of the calcium etc. in the lead.

What I claim is:-'

1. A process for preparing alkaline earth metal alloys which process comprises melting together a non-metallic compound of the said alkaline earth metal and aluminum and mixing therewith while in molten condition metallic lead and allowing the metal to form into two layers and separating the aluminium layer.

2. A process for the production of lead alkaline earth metal alloys, which process comprises reducing an alkaline earth metal with molten aluminum to form an aluminum alkaline earth metal alloy, and while the said alloy is in a molten condition adding lead thereto and allowing the same to settle through the molten alloy thereby to effect an alloying of the alkaline earth metal of the alloy with the lead, allowing the melt to form into two layers and separating the aluminum layer. g

3. A process for preparing alkaline earth metals, which process comprises in combination the steps of melting together an alkaline earth metal oxide in pieces more than 1 mm. in size and metallic aluminium; mixing therewith while in the molten condition metallic lead; allowing the melt to form into two layers;'separating the aluminium layer and separating by'known means the lead alkaline earth metal alloy into its constituent metals.

4. The process for the production of lead alkaline earth metal alloys, which process comprises reducing an alkaline earth metal with molten aluminum to form a aluminum alkaline earth metal alloy and while the said alloy is at a temperature of from 700 to 1000 C. adding metallic,

lead thereto and allowing the same to settle therethrough, thereby to eflect analloying of the alkaline earth metal of the alloy with the lead,

allowing the melt to form into two layers and sep-' I arating the aluminum layer.

5. The process which comprises reducing eal- I the aluminum layer.

6. A process for preparing calcium alloys which process comprises melting together calcium oxide in pieces more than 1 mm. in size and aluminium and mixing therewith while in the molten condition metallic lead and allowing the melt to form into two layers and separating the aluminium layer.

7. A process for preparing calcium alloys, which process comprises in combination the steps of melting together calcium oxide in pieces more than 1 mm. in size, and aluminium at a temperature 01' over 1000 C. maintaining the melt at about 1200 C. for some hours; reducing the temperature to 700-1000? 0.; mixing metallic lead and allowing the melt to form into two layers and separating the aluminium layer.

8. The process which comprises reducing magnes ium with molten aluminum to form an aluminum alloy containing magnesium, and while the said alloy is in a molten condition adding metallic lead thereto and allowing the same to settle therethrough. thereby to eflect an alloying of the magnesium with the lead, allowing the melt to form into two layers and separating the aluminum layer.

9. A process for preparing magnesium alloys,

which process comprises in combination the steps of melting together magnesite in pieces more than 1 mm. in size, and aluminium at a temperature of over 1000 C.; maintaining the melt at about 1200 C. for some hours: reducing the temperature to 700-1000" (3.: mixing metallic lead 

